Mouse CD38-Specific Heavy Chain Antibodies Inhibit CD38 GDPR-Cyclase Activity and Mediate Cytotoxicity Against Tumor Cells

Front Immunol. 2021 Sep 3:12:703574. doi: 10.3389/fimmu.2021.703574. eCollection 2021.

Abstract

CD38 is the major NAD+-hydrolyzing ecto-enzyme in most mammals. As a type II transmembrane protein, CD38 is also a promising target for the immunotherapy of multiple myeloma (MM). Nanobodies are single immunoglobulin variable domains from heavy chain antibodies that naturally occur in camelids. Using phage display technology, we isolated 13 mouse CD38-specific nanobodies from immunized llamas and produced these as recombinant chimeric mouse IgG2a heavy chain antibodies (hcAbs). Sequence analysis assigned these hcAbs to five distinct families that bind to three non-overlapping epitopes of CD38. Members of families 4 and 5 inhibit the GDPR-cyclase activity of CD38. Members of families 2, 4 and 5 effectively induce complement-dependent cytotoxicity against CD38-expressing tumor cell lines, while all families effectively induce antibody dependent cellular cytotoxicity. Our hcAbs present unique tools to assess cytotoxicity mechanisms of CD38-specific hcAbs in vivo against tumor cells and potential off-target effects on normal cells expressing CD38 in syngeneic mouse tumor models, i.e. in a fully immunocompetent background.

Keywords: CD38; NAD+; antibody engineering; antibody-dependent cellular cytotoxicity; complement-dependent cytotoxicity; heavy chain antibody; multiple myeloma; nanobody.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-ribosyl Cyclase 1 / genetics
  • ADP-ribosyl Cyclase 1 / immunology*
  • Animals
  • Antibodies, Monoclonal, Murine-Derived / genetics
  • Antibodies, Monoclonal, Murine-Derived / immunology*
  • Antibodies, Neoplasm / genetics
  • Antibodies, Neoplasm / immunology*
  • Antibody-Dependent Cell Cytotoxicity*
  • Cell Line, Tumor
  • Humans
  • Immunoglobulin Heavy Chains / genetics
  • Immunoglobulin Heavy Chains / immunology*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Neoplasms / immunology*

Substances

  • Antibodies, Monoclonal, Murine-Derived
  • Antibodies, Neoplasm
  • Immunoglobulin Heavy Chains
  • Membrane Glycoproteins
  • CD38 protein, human
  • ADP-ribosyl Cyclase 1